"fk378" <glam422@gmail.com> wrote in message news:33546210.1189959326672.JavaMail.jakarta@nitrogen.mathforum.org...> hello all!>> I'm having trouble with this problem:> Differentiate sin(t) + (pi)cos(t)>> So, I have f'(x) of sin(t) = cos(t)> Now what do I do with the (pi)cos(t) part? Do I say that the slope of pi > is zero, therefore the derivative of (pi)cos(t) is 0, then the answer > would be just sin(t) for the whole equation.>> OR>> Leave pi there, and have f'(x) of cos(t)= -sin(t) so that would make: > cos(t) + (pi)(-sin[t]) ???>> thank you!!

The latter, which can be written cost(t)-(pi)sin(t). Pi is constant but pi(-sin(t)) is not, anymore than (1)(cos(t)) is even though 1 is constant.